A small, four-rotor drone hovered over Washington Nationals players for a few days during spring training in Florida last month, taking publicity photos impossible for a human photographer to capture. But no one got the Federal Aviation Administration’s permission first.

Drones can be used for more than military maneuvers to fight terrorists abroad. Now police, the weather service and even private businesses are exploring the use of drones right here in the United States. But could these “eyes in the sky” see more than they’re supposed to?